The experiments proposed will examine the effects of stress on the physiological responses of the heart, vascular smooth muscle, liver and adipose tissue to epinephrine. Hypophysectomized rats will be used, and the manner by which growth hormone and glucocorticoids protect against stress will be examined, especially with respect to the possibility that the cyclic AMP system may be the site of stress-related impairment of homeostasis. The possibility that adrenal glucocorticoids and growth hormone offer protection against stress by maintaining the integrity of the cyclic AMP system will be studied.